In an internal combustion engine with a mechanical valve controller, scavenging air valve therein is controlled by a cam of a camshaft driven by a crankshaft. When phase between the crankshaft and the camshaft is fixed, a valve timing of the valve can be thus determined by arrangement and shape of the cam. According to the current working condition of the internal combustion engine, the valve timing of the valve can be adjusted by controlling the phase between the crankshaft and the camshaft, for achieving beneficial effects, such as reduced fuel consumption and less hazardous substance generated. This kind of apparatus for freely adjusting the phase between the crankshaft and the camshaft is referred to as a camshaft phaser.
Chinese patent application No. 201010212448.1 discloses a camshaft phaser. The camshaft phaser includes: an external rotor connected with a crankshaft in a drive manner, which is also referred to as a stator; an internal rotor concentrically set in a cavity of the stator, which is also referred to as a rotor; a front cover; a rear cover; a spring; and a plurality of mounting bolts. The front cover and the rear cover are respectively set at two sides of the stator, and the mounting bolts run through the stator so as to combine the front cover and the rear cover together. The spring has one end fixed on the front cover, and another end fixed on the rotor, thus the rotor is connected with the stator in a torsion-resistant manner. The spring is a compression one and extends for a certain distance along the axial direction. If there is no support for the spring, the spring will slant within the rotor, which may affect the installation process of the central bolt when fixing the rotor to the camshaft. Accordingly, in the camshaft phaser disclosed in this patent application, the front cover is configured to extend inwardly to form an annular supporting apparatus for supporting the front end of the spring, so as to effectively prevent the spring from slanting.
U.S. Pat. No. 6,450,137 also discloses a similar camshaft phaser, wherein a supporting apparatus is configured on the front cover or configured separately to prevent the spring from slanting. However, when the front cover is configured with a supporting apparatus, dimension of the front cover is increased and additional manufacturing cost is required. Furthermore, the supporting apparatus separately formed will increase the complexity of assembling the camshaft phaser and the manufacturing cost as well.
Therefore, a new camshaft phaser is needed.